\ ə-ˈlərt How to pronounce alert (audio) \

Definition of alert

 (Entry 1 of 3)

1a : watchful and prompt to meet danger or emergency an alert guard trying to stay alert to possible problems
b : quick to perceive and act mentally alert
2 : active, brisk elicited an alert response



Definition of alert (Entry 2 of 3)

1 : a state of careful watching and readiness especially for danger or opportunity on 24-hour alert
2a : an alarm or other signal of danger traffic alerts They sounded the alert.
b : an urgent notice … an alert to parents … about new immunization requirements.— Ann Schrader
3 : the period during which an alert is in effect
on the alert
: looking for or expecting something (such as danger or an opportunity) Drivers need to be on the alert for icy condition. always on the alert for a good bargain


alerted; alerting; alerts

Definition of alert (Entry 3 of 3)

transitive verb

1 : to call (someone) to a state of readiness : warn alerted the school board of a possible teachers' strike alert the authorities
2 : to make (someone) aware of something alerted the public to the dangers of pesticides

Other Words from alert


alertly adverb
alertness noun

Synonyms & Antonyms for alert

Synonyms: Adjective

Synonyms: Noun

Synonyms: Verb

Antonyms: Adjective

Visit the Thesaurus for More 

Choose the Right Synonym for alert


watchful, vigilant, wide-awake, alert mean being on the lookout especially for danger or opportunity. watchful is the least explicit term. the watchful eye of the department supervisor vigilant suggests intense, unremitting, wary watchfulness. eternally vigilant in the safeguarding of democracy wide-awake applies to watchfulness for opportunities and developments more often than dangers. wide-awake companies latched onto the new technology alert stresses readiness or promptness in meeting danger or in seizing opportunity. alert traders anticipated the stock market's slide

intelligent, clever, alert, quick-witted mean mentally keen or quick. intelligent stresses success in coping with new situations and solving problems. an intelligent person could assemble it fast clever implies native ability or aptness and sometimes suggests a lack of more substantial qualities. clever with words alert stresses quickness in perceiving and understanding. alert to new technology quick-witted implies promptness in finding answers in debate or in devising expedients in moments of danger or challenge. no match for his quick-witted opponent

Examples of alert in a Sentence

Adjective An alert guard stopped the robbers. He was tired and had trouble staying alert while he was driving. She wasn't mentally alert enough to answer the questions. An alert watchdog guarded the door. Noun They sounded an alert when enemy planes were approaching the city. Medical officials have put out an alert to hospitals to look out for the virus. The government has issued a terrorism alert. Verb Several neighbors alerted the authorities when they noticed strangers acting suspiciously. The governor alerted island residents that a hurricane was coming. The teacher alerted the students that tests would be given the next day. See More
Recent Examples on the Web: Adjective Another possibility is that New York City is just too loud for the relatively civilized decibel levels established for the alert systems by N.H.T.S.A. regulations. John Seabrook, The New Yorker, 1 Aug. 2022 While there is some truth to the claims that amphetamines have been used to keep soldiers alert in historical times of war, there is no scientific evidence of a gas existing that could keep anyone awake for 15 days. Emilia Benton, Men's Health, 28 July 2022 On Wednesday, CBS News chief medical correspondent Dr. Jonathan LaPook posted a video of Lear to Twitter, in which the TV legend shared his secrets to remaining healthy and alert at 100. Gina Martinez, CBS News, 27 July 2022 Many major cities in mainland China have equipped crosswalks with LED lights that shine up from the road to keep distracted jaywalkers alert. Dylan Butts, NBC News, 25 July 2022 This results in less strain on staffing and lowering of alert fatigue levels, allowing staff to be more focused on strategic and critical tasks such as patching and system hardening. Tony Bradley, Forbes, 25 July 2022 The Morgan County Sheriff’s Office issued an alert Sunday morning that George Joachim Ulrich, 40, and Richard Bono Sharpe were wanted after their unauthorized departure from work at a Decatur business. Lawrence Specker |, al, 24 July 2022 Japan's Sakurajima volcano erupts,prompting officials to issue highest alert. Editors, USA TODAY, 24 July 2022 Cuffari’s office did not directly respond to the allegations about the alert Wednesday. Carol D. Leonnig And Maria Sacchetti, Anchorage Daily News, 21 July 2022 Recent Examples on the Web: Noun But a novel or useful alert can become a meaningless repetitive noise over time. John Seabrook, The New Yorker, 1 Aug. 2022 Other school systems, such as Madison County Schools and Dothan City Schools, are installing new crisis alert systems that will enable school employees to get emergency help or activate a lockdown. al, 31 July 2022 Police in Woodstock, N.H., which is roughly 21 miles north of Ashland, responded to the alert by positioning officers along the highway. Nick Stoico,, 31 July 2022 In many homes, the only way that alert would have come through at that hour would have been a Wireless Emergency Alert on cell phones. Angela Fritz, CNN, 29 July 2022 Be the first to know about the biggest and best luxury home sales and listings by signing up for our Mansion Deals email alert. Katherine Clarke, WSJ, 29 July 2022 The Florida Department of Health in Broward issued the original rabies alert for parts of Davie on July 19. David J. Neal, Sun Sentinel, 28 July 2022 The man acted like the girl’s father to avoid suspicion, the alert said. Jake Sheridan, Chicago Tribune, 27 July 2022 The cases were unrelated to the current alert, as the spray had been imported from India, where B. pseudomallei is endemic. Erika Edwards, NBC News, 27 July 2022 Recent Examples on the Web: Verb The House passed a bipartisan bill Wednesday that would enable law enforcement to set a system to alert people, warning them in case of a nearby active shooter. Merdie Nzanga, USA TODAY, 14 July 2022 Thornton police Chief Glenn Beckman said such notification from the Postal Service might have enabled his department, early on, to alert people who had mailed checks using the collection boxes. Mike Nolan, Chicago Tribune, 13 July 2022 Ferrer did also say that the county health department has been using social media to alert people about monkeypox. Grace Toohey, Los Angeles Times, 8 July 2022 Because natural gas does not have a smell, an odorant is added to it, to help alert people if there is a leak. Globe Staff,, 28 June 2022 Sometimes the deminers will knock on doors in an area to personally alert people and keep them from worrying that the boom signals another Russian assault. Washington Post, 15 Apr. 2022 Smith did not seek any approval and did not alert dispatchers that he was involved in a chase, prosecutors say. From Usa Today Network And Wire Reports, USA TODAY, 6 June 2022 Smith did not seek any approval and did not alert dispatchers that he was involved in a chase, prosecutors say. Michael Balsamo, ajc, 3 June 2022 State officials approved the change in an email exchange with the lab and did not alert patients. Ginny Monk, Hartford Courant, 26 May 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'alert.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of alert


1618, in the meaning defined at sense 1a


1801, in the meaning defined at sense 1


circa 1868, in the meaning defined at sense 1

History and Etymology for alert


borrowed from French alerte, going back to Middle French a l'herte "on guard, on the watch," borrowed from Italian all'erta, originally in the collocation stare all'erta "to be on the watch," literally, "to be on the height" (with erta "height, hill, steep ascent," noun derivative from feminine of erto, past participle of ergere "to raise, elevate," going back to Vulgar Latin *ērgere, by syncope from Latin ērigere) — more at erect entry 1

Note: The earliest citation for the word in the Oxford English Dictionary suggests direct borrowing from Italian, or at least recognition of an Italian source: "In this place the Prince [of Orange] finding his rutters [cavalry soldiers] alert, (as the Italians say) with aduise of his valiant brother, hee sent his Trumpets to D. d' Alua …." (Sir Roger Williams, The Actions of the Lowe Countries, London, 1618, p. 27).


noun derivative of alert entry 1 (or borrowed from French alerte, derivative of alerte, adjective)


verbal derivative of alert entry 1 or alert entry 2

Buying Guide

Our Reviews team has selected the best home security camera systems.

Learn More About alert

Dictionary Entries Near alert




See More Nearby Entries 

Statistics for alert

Last Updated

4 Aug 2022

Cite this Entry

“Alert.” Dictionary, Merriam-Webster, Accessed 8 Aug. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More Definitions for alert


\ ə-ˈlərt How to pronounce alert (audio) \

Kids Definition of alert

 (Entry 1 of 3)

1 : watchful and ready especially to meet danger But he was alert at night, too, on the road, always listening intently …— Lois Lowry, The Giver
2 : quick to understand and act An alert reader noticed the error in grammar.

Other Words from alert

alertly adverb The prairie dog sat alertly beside the opening of its burrow.



Kids Definition of alert (Entry 2 of 3)

1 : an alarm or signal of danger The police issued an alert.
2 : the period during which an alert is in effect We stayed indoors during the alert.
on the alert
: watchful against danger … the remark had set us all on the alert, straining ears and eyes …— Robert Louis Stevenson, Treasure Island


alerted; alerting

Kids Definition of alert (Entry 3 of 3)

: to make aware of a need to get ready or take action : warn The siren alerted us that a tornado was approaching.

More from Merriam-Webster on alert

Nglish: Translation of alert for Spanish Speakers

Britannica English: Translation of alert for Arabic Speakers


Test Your Vocabulary

The Great British Vocabulary Quiz

  • union jack speech bubble
  • Named after Sir Robert Peel, what are British police called?
True or False

Test your knowledge - and maybe learn something along the way.

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!